1. Field of the Invention
The invention the subject of this application relates to cigarettes ad similar smoking articles, smoking material of which comprises expanded tobacco.
2. Brief Description of the Prior Art
It has been observed that when the cut tobacco filler of a cigarette includes a proportion of expanded tobacco, DIET-expanded tobacco for example, a smoker of the cigarette is likely to perceive that the mainstream smoke is hotter over the last few puffs than during the prior puffs.
An object of the subject invention is the provision of a smoking article, the smoking material of which comprises expanded tobacco, but which smoking article nevertheless provides to the smoker acceptable mainstream smoke over the whole of the smoking process.
It has also been observed that when smoking articles having a low density smoking material rod are wrapped with wrappers which, when wrapped around conventional density smoking material rods, effect a reduction in sidestream smoke constituents, the ratio of carbon monoxide (CO) to particulate matter, water and nicotine free (PMWNF), of the mainstream smoke is greater than one, i.e. there is little parity in CO and PMWNF. Efforts to reduce the CO to PMWNF ratio using a lower pressure drop cellulose acetate filter results in a more acceptable CO to PMWNF ratio but with poor smoking article mechanics, which mechanics are unacceptable to the smoker.
It is a further object of the subject invention to provide a smoking article which has acceptable smoke mechanics and a substantially matched CO to PMWNF ratio.